Volume fractions of DCE-MRI parameter as early predictor of histologic response in soft tissue sarcoma: A feasibility study

Abstract

ObjectiveTo find early predictors of histologic response in soft tissue sarcoma through volume transfer constant (Ktrans) analysis based on dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Materials and methods11 Patients with soft tissue sarcoma of the lower extremity that underwent preoperative chemoradiotherapy followed by limb salvage surgery were included in this retrospective study. For each patient, DCE-MRI data sets were collected before and two weeks after therapy initiation, and histologic tumor cell necrosis rate (TCNR) was reported at surgery. The DCE-MRI volumes were aligned by registration. Then, the aligned volumes were used to obtain the Ktrans variation map. Accordingly, three sub-volumes (with increased, decreased or unchanged Ktrans) were defined and identified, and fractions of the sub-volumes, denoted as F+, F- and F0, respectively, were calculated. The predictive ability of volume fractions was determined by using area under a receiver operating characteristic curve (AUC). Linear regression analysis was performed to investigate the relationship between TCNR and volume fractions. In addition, the Ktrans values of the sub-volumes were compared. ResultsThe AUC for F- (0.896) and F0 (0.833) were larger than that for change of tumor longest diameter ΔD (0.625) and the change of mean KtransΔKtrans¯ (0.792). Moreover, the regression results indicated that TCNR was directly proportional to F0 (R2=0.75, P=0.0003), while it was inversely proportional to F- (R2=0.77, P=0.0002). However, TCNR had relatively weak linear relationship with ΔKtrans¯ (R2=0.64, P=0.0018). Additionally, TCNR did not have linear relationship with DD (R2=0.16, P=0.1246). ConclusionThe volume fraction F- and F0 have potential as early predictors of soft tissue sarcoma histologic response.